In a long line of people waiting for a bank teller, one guy suddenly started massaging the back of the person in front of him.
Surprised, the man in front turned and snarled, "Just what the hell are you doing?"
"Well," said the guy, "you see, I'm a chiropractor and I could see that you were tense, so I had to massage your back. Sometimes I just can't help practicing my art!"
"That's the stupidest thing I've ever heard!" the guy replied. "I'm a lawyer. Do you see me screwing the guy in front of me?"